In the field of process automation technology, in many cases, field devices are used for registering and influencing process variables. Examples of field devices are temperature measuring devices, which register the temperature of a medium; flow rate meters, which register the flow rate of a medium in a section of piping; or fill level meters, which register the fill level of a liquid or bulk goods in a container.
Field devices are normally connected via a data or field bus with superordinated control units, e.g. process control systems PCS or an engineering system, from which the process activity is controlled or monitored, and also from which direct access to individual field devices is possible. As a result of the direct access to the field device, settings at the field device can be changed from the control unit, or diagnostic functions of the field device can be called up. In the control unit, the measurement values of the different sensors are evaluated or monitored, and, for process control, the appropriate actuators are activated. Data transfer between field device and control units is carried out according to known international standards for field buses, such as e.g. HART®, Foundation Fieldbus®, Profibus®, or CAN-Bus®, etc.
Frequently in process automation technology, field devices from different manufacturers are used. The servicing, or operating, of field devices is carried out by means of PC-based applications, which especially support the parameterization, start-up, and diagnostics of individual field devices, in part also graphically.